Motion estimation with dual search windows for high resolution video coding

Abstract

A memory-efficient motion estimation technique for high-resolution video coding is proposed. The main objective is to reduce the external memory access, especially for limited local memory resource. The reduction of memory access can successfully save the notorious power consumption. The key to reduce the memory access is based on center-biased algorithm in that the center-biased algorithm performs the motion vector searching with the minimum search data. While considering the data reusability, the proposed dual-search-windowing approaches use a secondary windowing as an option per searching necessity, by which the loading of search windows can be alleviated and hence reduce the required external memory bandwidth, without significant quality degradation.

1 . A dual-search-windowing motion estimation method for high-resolution video coding, comprising the steps of:
 determining a range for a primary window from a full search range according to a statistical material of motion vector occurrence positions;   determining an initial point for starting a motion vector search with a predicted motion vector; and   loading a secondary window for the motion vector search when the initial point or a tracking of the motion vector search is out of the range of the primary window.   
   
   
       2 . The method of  claim 1 , further comprising the step of determining a range for the secondary window. 
   
   
       3 . The method of  claim 2 , wherein the step of determining a range for the secondary window comprises the step of selecting a quarter of the full search range as the range of the secondary window. 
   
   
       4 . The method of  claim 2 , wherein the step of determining a range for the secondary window comprises the step of determining the range of the secondary window according to a statistical material of a motion estimation in the full search range. 
   
   
       5 . The method of  claim 2 , wherein the step of determining a range for the secondary window comprises the step of determining the range of the secondary window according to a sum of absolute differences of the predicted motion vector. 
   
   
       6 . A dual-search-windowing motion estimation system for high-resolution video coding, comprising:
 a first on-chip memory for storing a primary window loaded from an external memory;   a second on-chip memory; and   a circuit for determining to load a secondary window from the external memory to the second on-chip memory when an initial point or a tracking of a motion vector search is out of the primary window.   
   
   
       7 . The system of  claim 6 , further comprising a padding circuit for padding the primary window and the secondary window with a padding algorithm. 
   
   
       8 . A padding method for a motion estimation including loading a search window in a current frame for a motion vector search, the padding method comprising the steps of:
 performing the motion vector search in a range of the search window contained in the frame when the search window goes outside the frame; and   when a tracking of the motion vector search is out of the frame, generating padding data outside the frame by reproducing and extending data at a boundary of the frame and performing the motion vector search accordingly.   
   
   
       9 . The method of  claim 8 , further comprising the step of performing the motion vector search with a search model. 
   
   
       10 . The method of  claim 9 , further comprising the step of determining whether or not the search model goes outside the frame according to a leftmost pixel coordinate in the search model.